Study On The Interfacial Microstructure And Properties Of Dissimilar Alloy Bonded By Plastic Deformation

With the increasing application of magnesium alloy and aluminum alloy,it is necessary to develop the bonding technology of magnesium alloy and aluminum alloy in order to reduce the weight of structural parts,improve their performance and production efficiency.The high-quality and high-strength bonding of dissimilar metals can give full play to the advantages of each material and meet the manufacturing requirements of high performance and lightweight in modern production.In this paper,the plastic deformation bonding process of AZ31 B magnesium alloy and AA6061 aluminum alloy was systematically studied.The effects of bonding temperature,deformation and surface roughness on plastic deformation bonding were analyzed.The plastic deformation bonding mechanism of Mg/Al dissimilar alloy was discussed.This study enriches and expands the plastic deformation bonding process,and provides theoretical and practical basis for the plastic deformation bonding of Mg/Al dissimilar alloy.The main results are as follows:Firstly,the plastic deformation bonding process of dissimilar alloy was numerically simulated by Deform software.The equivalent stress field and equivalent strain field were analyzed,and select a feature point at the bonding interface,the magnesium alloy side of the bonding interface,and the aluminum alloy side of the bonding interface for analysis,and study the variation of stress and strain at the feature point with bonding temperature and deformation.Secondly,through the plastic deformation bonding experiment of AZ31 B magnesium alloy and AA6061 aluminum alloy,the microstructure and morphology of the plastic deformation bonding interface under different bonding temperatures and deformations were analyzed,and the interface bonding mechanism was analyzed from two aspects of plastic deformation and diffusion.The element distribution and phase composition of the bonding interface were analyzed by EDS and XRD,and the mechanical properties of the joints after bonding were tested.With the increase of deformation and temperature,the bonding strength first increased and then decreased.When the bonding temperature was 400°C and the deformation was 50%,The tensile strength reaches a maximum of 112.3MPa.Finally,the plastic deformation bonding experiments of magnesium/aluminum alloy samples with different surface roughness were carried out to study the effect of surface roughness on the microstructure and properties of plastic deformation bonding interface.The experimental results show that with the decrease of the surface roughness of the sample,the bonding interface is gradually smooth and the thickness of the diffusion layer increases.When the surface roughness is low,the interface grain boundary migration mainly occurs at the intersection of the three grains,forming a wedge between the three grains.When the surface roughness is high,more strain-induced interfacial grain boundary migration occurs on the bonding interface.With the decrease of the surface roughness of the sample,the bonding strength increases first and then decreases.When the roughness is moderate,the tensile strength of the plastic deformation bonding sample reaches a maximum of 114.15MPa.